Different countries around the world have power sources that generate voltages of different magnitudes. For example, in many European countries standard power sources output 200 AC volts at a frequency of 50 hertz, while in the United States standard power sources generate 110 AC volts at a frequency of 60 hertz.
Electrical equipment is generally designed to operate at specific voltage ranges that are compatible with standard power sources that generate particular AC voltages. In order to use the same piece of electrical equipment with a voltage source generating a different voltage value, an adapter must be used to ensure that the voltage generated by the voltage source is adapted to a voltage magnitude that can be used by the equipment. The use of an adapter enables electrical equipment with specific voltage specifications to be used worldwide.
Adapters are electrical devices that accept a specific voltage as sm input and generate a predetermined output voltage. For example, a device may be designed to operate at 110 AC volts. This same device can be driven from a power source that generates 200 AC volts if an adapter that converts 200 AC volts to 110 AC volts is connected between the power source and the device.
Prior art adapters have used transformers with multiple voltage taps where the appropriate taps have been hard wired to generate a particular output voltage in response to a specific AC input voltage to the transformer. These adapters are tailor made to operate with a specific input voltage value to the transformer generating a predetermined output voltage. This requires the use of multiple adapters with different adapter plug configurations for power sources with different voltage values.
Many adapters have transformers with multiple taps and multiple modular adapter plugs designed to operate with different power sources generating different AC voltage values. Configuring the transformer to operate with a compatible power source generally involves two steps: using a switch to select the appropriate transformer taps, and selecting the appropriate modular adapter plug that is compatible with the power source being used.
Clearly it would be desirable to use a transformer where a single step could be performed to both select the appropriate transformer taps and configure the transformer to be physically compatible with the power source to be used. This would reduce the possibility of human error and potential damage to often expensive electrical equipment.